Preparation of china-clay.



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rnnrAnA'rIon Be it'known that we, ALFRED combs SALAMoN, F.-I. CL, consulting-and analyti- ,Steyning, Sussex,

cal chemist, and CHARLES J nENsGRAcn, A. I. M. M., subjects of the King of Great Britain, residing, respectively, at 1 F enchurch avenue, London, "and Chantry Green House, England, have; invented a new and useful Preparation of China-Clay, of which the following is a specification.

This invention relates to improvements in the preparation of china clay 'ashitherto practised. a y

A largeproportion of the china clay put upon the market is used forbleaching pur-' poses and-its selling value iS tO a very great extent dependent uponits freedom from color. 1

can be almost entirely, if not wholly, removed by subjecting, an'emulsion of the clay, z. e., particles .of clay suspended in water,

whether concentrated or, comparatively diluteto the action of a suitable sulfite which acid or a bisulfite or other compound of sulfurous acid which is capableof combining with the coloring matterand forming solu U ble salts or-compounds. The quantity of reagent required, which is very small com pared to the quantity of clay to be treated,

' will be'dependent upon the amount of color ingunatter to be removed and may be de-' I t'ermined'by previous experiment upon the press be used small scale. If, as is preferable, a filter for subsequent treatment of the-"china clay, we advise that the china clay while in the press be well washed with waterso asyto remove. practically the whole, if

notfthe-whole, of the added reagent and any soluble salts or compounds which it may have formed. -We have found-that by such. treatment the value of the product obtained is greatly enhanced and further that a low or second quality clay may by sucheliminatio'n of the objectionable constituent-or conor crime-c ar.

.Stituents be fairly broughtinto the category of first quality clays suitable for use n bleaching.

The process of treatment above described v Specification of Letters Patent. Patented Jn1y16, 1912. Application filed. December 4,1909. Si'ia1li1'o .531,392. y

a will also apply; to china clay sold as otters clay provided that the emulsion oes not contain an undue pfdportion of mica containing coloring matter. Shouldthis be the case then, the coloring matter above referred to is liable to become visible upon firing.

Whatwe claim is 1. In the preparation of china clay; the

process of decolorizing the clay, which consists' in subjecting it to the action alone of,

a'sulfite capable of combining with the coloring matter and'forming soluble salts or H v compounds. We have found that the'coloring matter *2; In the preparation of china delay the process for decolorizing the clay, which con- ,sists in subjecting it to the action of sulfurous' acid alone.

3. In the preparationof china clay the process for decoloriz ingthe clay. which conmay be hydrogen sulfite that is sulfurous sists in subjecting an emulsion of the clay then filtering the emulsion by pressure.

to the action'of s'ulfurous acid alone, then filtering the emulsion by, pressure and washing the filtered clay.

5.. In the preparation of china cla'y, the

process herein described for decolorizing 'tothe action of. sulfurous acid alone and f the clay which consists in subjecting an. I

emulsion of the clay to the action alone of a sulfite capable of combining with the coloring matter and forming compounds.

ALFRED GORDON SADAMON. CHARLES JEENS GRACE.

.-Witnesses:

a C ARLES EDWIN FAIRH ALL; HAnRY WILLES.

soluble salts or 

